Hemangiopericytoma

Stout and Murray in 1942 were the first to suggest hemangiopericytoma as a distinctly different vascular neoplasm. Stout also was the first to report an oral hemangiopericytoma, just a few years after its initial delineation. It is a neoplasm which is usually benign but has a definite malignant counterpart. Head and neck lesions represent 16-25% of all reported hemangiopericytomas, and the tumor represents 2-3% of all soft tissue sarcomas in humans.  Chromosomal translocations t(12;19) and t(13;22) have been observed in lesional cells.

The oral hemangiopericytoma is typically a rapidly enlarging red or bluish mass which arises in all age groups but is rare prior to the second decade or after the seventh decade.  There is no gender predilection. It is soft or rubbery, is usually painless and is relatively well demarcated from the surrounding mucosa. The lesion may be sessile or somewhat pedunculated, and may demonstrate a surface lobularity or telangiectasis. Intraosseous examples have been reported.

The oral/pharyngeal mucosa is, additionally, one of the most common locations for the rarely reported infantile hemangiopericytoma.  This lesion is usually multiple and congenital, and often demonstrates an alarmingly rapid rate of enlargement after birth. Although this entity tends to recur after surgical excision, there is no potential for metastasis.

Hemangiopericytoma consists of numerous vascular channels with plump endothelial nuclei and a surrounding, tightly packed proliferation of oval and spindled cells with dark nuclei and a moderate amount of cytoplasm.  Areas with more spindled pericytes may show an interlacing pattern of cells but usually there is a medullary tissue pattern, sometimes with palisading of cells, reminiscent of a neural tumor. Older, less aggressive lesions tend to have less cellularity and may have a largely mucoid interstitial appearance, which can be mistaken for myxoid lipoma or myxoid liposarcoma. Focal cartilage production may rarely be seen and such lesions must be differentiated from mesenchymal chondrosarcoma.

The number of mitotic figures is variable and of prognostic significance, with lesions showing fewer than 2-3 mitotic figures per high-power field having a slower growth, lesser recurrence rate and fewer metastases than lesions with four or more mitotic figures per high power field. Lesions with pleomorphic cells and areas of necrosis or hemorrhage usually have a more aggressive behavior than those without these features.

Reticulin staining will demonstrate lesional vessels lined by a single layer of endothelial cells, with the pericytes lying outside the basal lamina, although they are often individually surrounded by reticulin and collagen fibers. Lesional cells are immunoreactive for vimentin (variable intensity), factor XIIIa antigen, HLA-DR antigen and QBEND10 (CD34).  They do not stain for or react with factor VIII-related antigen, Ulex europaeus I lectin, alpha-smooth muscle actin, desmin, myoglobin, low-molecular weight cytokeratin, high-molecular weight cytokeratin, or epithelial membrane antigen.

The differential diagnosis of this lesion includes, in addition to the tumors named above, fibrous histiocytoma, MFH, synovial sarcoma, other stromal sarcomas, juxtaglomerular tumor, vascular leiomyoma, and juvenile hemangioma.

The treatment of hemangiopericytoma is dependent on the amount of cellular dysplasia and mitotic activity. The more bland lesions with minimal mitotic activity are treated by wide local excision, but the more active and dysplastic lesions are treated by radical surgical excision, with or without adjunctive radiotherapy.  Surgical removal is usually preceded by ligation of the feeder vessels or by embolization to reduce the size of the tumor and the risk of operative hemorrhage.

The rate of metastasis for this tumor during the first five year postoperative period varies from 17-56%, and metastasis occasionally occurs up to 10 years after surgery.  Metastases are usually to the lungs and bones; lymph node metastasis is uncommon. Most recurrent tumors will eventually demonstrate metastasis. The overall five-year survival rate for the microscopically dysplastic hemangiopericytoma is somewhat less than 50%.

Stout AP, Murray MR. Hemangiopericytoma: vascular tumor featuring Zimmermann's pericytes. Ann Surg 1942; 116:26.

Walike JW, Bailey BJ. Head and neck hemangiopericytoma. Arch Otolaryngol 1971; 93:345-353.

Seibert JJ. Multiple congenital hemangiopericytomas of the head and neck. Laryngoscope 1978; 88:1006-1012.

Alpers CE, Rosenau W, Finkbeiner WE, et al. Congenital (infantile) hemangiopericytoma of the tongue and the sublingual region. Am J Clin Pathol 1984; 81:377-382.

Abdel-Fattah HM, Adams GL, Wick MR. Hemangiopericytoma of the maxillary sinus and skull base. Head Neck 1990; 12:77-83.

Daniels RL, Haller JR, Harnsberger HR. Hemangiopericytoma of the masticator space. Ann Otol Rhin Laryngol 1996; 105:162-165.

Delgaudio JM, Garetz SL, Bradford CR, Stenson KM. Hemangiopericytoma of the oral cavity. Otolaryngol Head Neck Surg 1996; 114:339-340.

Kothari PS, Murphy M, Howells GL, Williams DM. Hemangiopericytoma - a report of 2 cases arising on the lip. Brit J Oral Maxillofac Surg 1996; 34:454-456.

Lin JC, Hsu CY, Jan JS, Chen JT. Malignant hemangiopericytoma of the floor of the mouth - report of a case and review of the literature. J Oral Maxillofac Surg 1996; 54:1020-1023.

Perkins P, Weiss SW. Spindle cell hemangiopericytoma - an analysis of 78 cases with reassessment of its pathogenesis and biologic behavior. Amer J Surg Pathol 1996; 20:1196-1204.